When using Serato DJ Pro, I hear an echo-like sound from headphones or speakers connected to [MASTER 1]/[ MASTER 2] even when I'm not playing. Why?

Change the setting as follows.

・In Serato DJ Pro, open [Setup] > [Audio] and remove the check mark for [Use Laptop Speakers].

・If you want to keep the check mark, change the setting as follows.

■Windows

Open [Sound] > [Output] and select your PC's built-in speaker.

■Mac

Open [Audio MIDI Setup] > [Audio Devices], select your Mac speaker, right-click, and select [Use This Device For Sound Output].